cdc.gov/coronavirus

COVID-19 Vaccine safety updates

Advisory Committee on Immunization Practices 

(ACIP)

June 23, 2021

Tom Shimabukuro, MD, MPH, MBA

Vaccine Safety Team

CDC COVID-19 Vaccine Task Force
2

Disclaimer

▪ The findings and conclusions in this report are those of the authors 

and do not necessarily represent the official position of the Centers 

for Disease Control and Prevention (CDC) or the U.S. Food and Drug 

Administration (FDA)

▪ Mention of a product or company name is for identification 

purposes only and does not constitute endorsement by CDC or FDA
3

Topics

▪ Early safety data of Pfizer-BioNTech vaccination in persons aged 

12–15 years old

▪ Myocarditis and pericarditis following mRNA COVID-19 vaccination
4

Early safety data of Pfizer-BioNTech vaccination in persons 

aged 12–15 years old
5

http://cdc.gov/vsafe

Smartphone-based active safety monitoring
6

Overview of v-safe monitoring of Pfizer-BioNTech

COVID-19 vaccine for younger adolescents

▪ On May 11, 2021, v-safe age limits expanded to allow registration 

down to 12 years of age at dose 1

▪ As of June 13, for persons age 12–15 years after Pfizer-BioNTech

COVID-19 vaccination:

‒ 57,126 with at least one health check-in during days 0–7 after dose 1

‒ 15,988 with at least one health check-in during days 0–7 after dose 2
7

V-safe: Top solicited reactions reported at least once in days 0–7 after 

vaccination with Pfizer-BioNTech in 12–15-year-olds vs. 16–25-year-olds*

(data thru Jun 13, 2021)

*

Includes participants who completed at least one survey in the first week after dose 1 of Pfizer-BioNTech COVID-19 vaccine

Dose 1 Pfizer-BioNTech

COVID-19 vaccination

Dose 2 Pfizer-BioNTech

COVID-19 vaccination
8

V-safe: Health Impact Events reported at least once in days 0-7 after 

vaccination with Pfizer-BioNTech in 12–15-year-olds vs. 16–25-year-olds*

(data thru Jun 13, 2021)

*

Includes participants who completed at least one survey in the first week after dose 1 of Pfizer-BioNTech COVID-19 vaccine

Dose 1 Pfizer-BioNTech

COVID-19 vaccination

Dose 2 Pfizer-BioNTech

COVID-19 vaccination

Medical care in 

emergency 

dept/hospital:

12-15 years: 0.1%

16-25 years: 0.1%

Medical care in 

emergency 

dept/hospital:

12-15 years: 0.2%

16-25 years: 0.2%
9

+

co-managed by

CDC and FDA

Vaccine Adverse Event 

Reporting System

http://vaers.hhs.gov

VAERS is the nation’s early warning system for vaccine safety
10

VAERS

key strengths

▪ Rapidly detects potential 

safety problems 

▪ Can detect rare adverse 

events

key limitations

▪ Inconsistent quality and 

completeness of information

▪ Reporting biases

▪ Generally, cannot determine 

cause and effect

VAERS accepts all reports from everyone regardless 

of the plausibility of the vaccine causing the event or 

the clinical seriousness of the event
11

Source: Shimabukuro et al. Safety monitoring in 

the Vaccine Adverse Event Reporting System 

(VAERS). Vaccine. 2015 Aug 26;33(36):4398-405.

What’s in VAERS?

Does not 

necessarily mean 

vaccination caused 

a health problem
12

Reports to VAERS after Pfizer-BioNTech COVID-19 vaccination: 

persons aged 12–15 years vs. 16–25 years*(data thru Jun 11, 2021)

Ages N

Crude reporting rate 

(per million doses)

Non-serious

adverse events (%)

Serious adverse 

events‡,§(%)

12–15 years old 2,540 422 2,396 (94.3) 144 (5.7)

16–25 years old†

(for comparison) 12,759 592 11,969 (93.8) 790 (6.2)

* Data as of June 14, 2021, for reports with vaccination date and receipt date May 10 through June 11, 2021

† Data as of June 14, 2021, for reports with vaccination date and receipt date December 14, 2020, through June 11, 2021

‡ Based on the Code of Federal Regulations if one of the following is reported: death, life-threatening illness, hospitalization or prolongation of hospitalization, permanent disability, congenital anomaly or birth defect

§

Includes 1 report of death in the 12–15-year-old age group and 18 reports of death in the 16–25-year-old age group

▪ 12–15 years old: ~6.0 million doses administered (May 10 thru June 11, 2021)

▪ 16–25 years old: ~21.6 million doses administered (December 14, 2020, thru June 11, 2021)
13

Most commonly reported adverse events to VAERS after 

Pfizer-BioNTech COVID-19 vaccination*(data thru Jun 11, 2021) 

* Data as of June 14, 2021, for reports with vaccination date and receipt date May 10 through June 11, 2021

† Data as of June 14, 2021, for reports with vaccination date and receipt date December 14, 2020, through June 11, 2021

‡ Adverse events are not mutually exclusive

Adverse event‡ n (%)

Dizziness 618 (24.3)

Syncope 446 (17.6)

Nausea 308 (12.1)

Headache 281 (11.1)

Vomiting 221 (8.7)

Pallor 218 (8.6)

Loss of consciousness 217 (8.5)

Pyrexia (fever) 215 (8.5)

Hyperhidrosis 211 (8.3)

Fatigue 182 (7.2)

Adverse event‡ n (%)

Dizziness 2,832 (22.2)

Headache 2,197 (17.2)

Nausea 1,955 (15.3)

Pyrexia (fever) 1,948 (15.3)

Fatigue 1,689 (13.2)

Chills 1,609 (12.6)

Pain 1,560 (12.2)

Syncope 1,257 (9.9)

Hyperhidrosis 946 (7.4)

Vomiting 918 (7.2)

12–15 years old*(N= 2,540) 16–25 years old†

(N= 12,759)

(for comparison)

▪ 12–15 years old: ~6.0 million doses administered (May 10 thru Jun 11, 2021)

▪ 16–25 years old: ~21.6 million doses administered (December 14, 2020, thru Jun 11, 2021)
14

Myocarditis and pericarditis following mRNA COVID-19 

vaccination in the United States
15

+

co-managed by

CDC and FDA

Vaccine Adverse Event 

Reporting System

http://vaers.hhs.gov

VAERS is the nation’s early warning system for vaccine safety
16
17

Preliminary myocarditis/pericarditis reports to VAERS following 

mRNA COVID-19 vaccination by dose number 

(after ~300 million mRNA doses administered, data thru Jun 11, 2021)

Manufacturer

Reports after

dose 1 

Reports after 

dose 2

Reports after

unknown dose

Pfizer-BioNTech (n=791) 150 563 78

Moderna (n=435) 117 264 54

Total (N=1,226) 267 827 132

▪ Includes total preliminary reports identified through VAERS database searches for reports with 

myocarditis/pericarditis MedDRA* codes and pre-screened VAERS reports with signs and 

symptoms consistent with myocarditis/pericarditis

‒ Follow-up, medical record review, application of CDC working case definition, and 

adjudication is ongoing or pending

* Medical Dictionary for Regulatory Activities https://www.meddra.org/
18

Characteristics of preliminary* myocarditis/pericarditis reports to 

VAERS following mRNA COVID-19 vaccination (data thru Jun 11, 2021)

Characteristics

Dose 1 

(n=267)

Dose 2 

(n=827)

Median age, years (range) 30 (12–94) 24 (12–87)

Median time to symptom onset, days (range) 4 (0–61)† 3 (0–98)†

Sex (%)

Male 176 (66%) 655 (79%)

Female 88 (33%) 165 (20%)

Not reported/not available 3 (1%) 7 (1%)

* Includes total reports identified through VAERS database searches for reports with myocarditis/pericarditis MedDRA codes and pre-screened VAERS reports with signs and 

symptoms consistent with myocarditis/pericarditis (and with dose number documented); Follow-up, medical record review, application of CDC working case definition, and 

adjudication is ongoing or pending

† One report of 179-day onset after dose 1; one report of 151-day onset after dose 2 – included in counts, but not in range
19

0

5

10

15

20

25

30

35

40

45

50

55

60

65

70

12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48 50

Preliminary reports

Age of reported patient, years

Dose 1 Dose 2

Preliminary reports of myocarditis/pericarditis to VAERS after 

mRNA COVID-19 vaccination by age and dose number*

(as of Jun 11, 2021)

* Age truncated at >50yr: 

Reports of persons >50yr 

of age include 70 after 

Dose 1, 119 after Dose 2
20

Preliminary reports of myocarditis/pericarditis to VAERS after mRNA 

COVID-19 vaccination by dose number and time to symptom onset*

(as of Jun 11, 2021)

* Reports of time to 

symptom onset 

truncated at >29 days: 

Includes 5 reports after 

Dose 1, 56 after Dose 2

0

20

40

60

80

100

120

140

160

180

200

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29

Preliminary reports

Time from vaccination to symptom onset, days

Dose 1 Dose 2
21

416

117

295 310

81

0

50

100

150

200

250

300

350

400

450

Chest pain Dyspnea ST or -T wave change Elevated cardiac enzymes Abnormal echocardiography

/ imaging

Number of identified reports

Symptom or diagnostic findings

Symptoms and diagnostic findings of preliminary 

myocarditis/pericarditis reports after mRNA COVID-19 

vaccination under review, limited to ≤29 years old (N=484)

(data thru Jun 11, 2021)
22

Care and outcomes of preliminary myocarditis/pericarditis cases reported 

to VAERS after mRNA COVID-19 vaccination in persons <29 years old 

(N=484) (data thru Jun 11, 2021)

484 total preliminary reports

▪ 323 have met CDC working 

case definition of myocarditis 

or pericarditis (or both)

▪ 148 are under review

Of 323 meeting case definition:

▪ 309 were hospitalized 

‒ 295 discharged

• 218 (79%) known to have 

recovered from symptoms 

at time of report

‒ 9 still hospitalized (2 in ICU)

‒ 5 without outcome data

▪ 14 were not hospitalized (seen in 

emergency dept., urgent care, 

outpatient clinic, not specified)
23

CDC working case definition for acute myocarditis
24

CDC working case definition for acute pericarditis
25

Preliminary myocarditis/pericarditis reports to VAERS following dose 1 mRNA 

COVID-19 vaccination, Exp. vs. Obs. using 21-day risk window (data thru Jun 11, 2021)

Age groups

Females Male

Doses 

admin Expected*,† Observed*

Doses 

admin Expected*,† Observed*

12–17 yrs 3,777,097 1–13 4 3,569,239 2–21 32

18–24 yrs 6,830,706 2–23 9 5,863,268 3–34 47

25–29 yrs 5,198,356 2–18 3 4,685,036 3–27 18

30–39 yrs 11,505,068 7–66 15 10,391,499 6–60 17

40–49 yrs 11,996,507 7–69 9 10,513,258 6–60 8

50–64 yrs 21,957,007 13–126 22 19,270,825 11–111 18

65+ yrs 24,795,212 14–143 13 20,473,779 12–118 15

Not reported — — 2 — — 4

* Assumes a 21-day post-vaccination observation window (i.e., symptom onset from day of vaccination through Day 20 after vaccination)

† Based on Gubernot et al. U.S. Population-Based background incidence rates of medical conditions for use in safety assessment of COVID-19 vaccines. Vaccine. 2021 May 14:S0264-

410X(21)00578-8. Expected counts among females 12–29 years adjusted for lower prevalence relative to males by factor of 1.7 (Fairweather, D. et al, Curr Probl Cardiol. 2013;38(1):7-46). 
26

Preliminary myocarditis/pericarditis reports to VAERS following dose 1 mRNA 

COVID-19 vaccination, Exp. vs. Obs. using 7-day risk window (data thru Jun 11, 2021)

Age groups

Females Males

Doses 

admin Expected*,† Observed*

Doses 

admin Expected*,† Observed*

12–17 yrs 3,777,097 0–4 3 3,569,239 1–7 27

18–24 yrs 6,830,706 1–8 6 5,863,268 1–11 41

25–29 yrs 5,198,356 1–6 2 4,685,036 1–9 14

30–39 yrs 11,505,068 1–13 8 10,391,499 2–20 14

40–49 yrs 11,996,507 1–14 1 10,513,258 2–20 5

50–64 yrs 21,957,007 2–25 16 19,270,825 4–37 10

65+ yrs 24,795,212 2–25 8 20,473,779 4–39 8

Not reported — — 2 — — 2

* Assumes a 7-day post-vaccination observation window (i.e., symptom onset from day of vaccination through Day 6 after vaccination)

† Based on Gubernot et al. U.S. Population-Based background incidence rates of medical conditions for use in safety assessment of COVID-19 vaccines. Vaccine. 2021 May 14:S0264-

410X(21)00578-8. Expected counts among females 12–29 years adjusted for lower prevalence relative to males by factor of 1.7 (Fairweather, D. et al, Curr Probl Cardiol. 2013;38(1):7-46). 
27

Preliminary myocarditis/pericarditis reports to VAERS following dose 2 mRNA 

COVID-19 vaccination, Exp. vs. Obs. using 21-day risk window (data thru Jun 11, 2021)

Age groups

Females Males

Doses 

admin Expected*,† Observed*

Doses 

admin Expected*,† Observed*

12–17 yrs 2,189,726 1–7 20 2,039,871 1–12 132

18–24 yrs 5,237,262 2–18 27 4,337,287 2–25 233

25–29 yrs 4,151,975 1–15 11 3,625,574 2–21 69

30–39 yrs 9,356,296 5–54 14 8,311,301 5–48 71

40–49 yrs 9,927,773 6–57 23 8,577,766 5–49 40

50–64 yrs 18,696,450 11–108 25 16,255,927 9–94 34

65+ yrs 21,708,975 12–125 17 18,041,547 10–104 16

Not reported — — 1 — — 9

* Assumes a 21-day post-vaccination observation window (i.e., symptom onset from day of vaccination through Day 20 after vaccination)

† Based on Gubernot et al. U.S. Population-Based background incidence rates of medical conditions for use in safety assessment of COVID-19 vaccines. Vaccine. 2021 May 14:S0264-

410X(21)00578-8. Expected counts among females 12–29 years adjusted for lower prevalence relative to males by factor of 1.7 (Fairweather, D. et al, Curr Probl Cardiol. 2013;38(1):7-46). 
28

Preliminary myocarditis/pericarditis reports to VAERS following dose 2

mRNA vaccination, Exp. vs. Obs. using 7-day risk window (data thru Jun 11, 2021)

Age groups

Females Males

Doses 

admin Expected*,† Observed*

Doses 

admin Expected*,† Observed*

12–17 yrs 2,189,726 0–2 19 2,039,871 0–4 128

18–24 yrs 5,237,262 1–6 23 4,337,287 1–8 219

25–29 yrs 4,151,975 0–5 7 3,625,574 1–7 59

30–39 yrs 9,356,296 2–18 11 8,311,301 2–16 61

40–49 yrs 9,927,773 2–19 18 8,577,766 2–16 34

50–64 yrs 18,696,450 4–36 18 16,255,927 3–31 18

65+ yrs 21,708,975 4–42 10 18,041,547 3–35 11

Not reported — — 1 — — 8

* Assumes a 7-day post-vaccination observation window (i.e., symptom onset from day of vaccination through Day 6 after vaccination)

† Based on Gubernot et al. U.S. Population-Based background incidence rates of medical conditions for use in safety assessment of COVID-19 vaccines. Vaccine. 2021 May 14:S0264-

410X(21)00578-8. Expected counts among females 12–29 years adjusted for lower prevalence relative to males by factor of 1.7 (Fairweather, D. et al, Curr Probl Cardiol. 2013;38(1):7-46). 
29

Preliminary myocarditis/pericarditis crude reporting rates to 

VAERS following mRNA COVID-19 vaccination (data thru Jun 11, 2021)

Overall reporting

rate per million doses

Reporting rate in females

per million doses

Reporting rate in males

per million doses

Age groups All doses Dose 1 Dose 2 All doses Dose 1 Dose 2 All doses Dose 1 Dose 2

12-17 yrs 18.1 5.3 37.0 4.2 1.1 9.1 32.4 9.8 66.7

18-24 yrs 15.9 4.8 28.4 3.6 1.5 5.5 30.7 8.7 56.3

25-29 yrs 6.7 2.5 10.8 2.0 0.8 2.6 12.2 4.5 20.4

30-39 yrs 4.2 1.7 5.6 1.8 1.4 1.8 6.9 2.0 10.0

40-49 yrs 2.7 0.9 3.8 2.0 0.9 2.8 3.5 1.0 5.1

50-64 yrs 1.7 1.0 2.0 1.6 1.0 1.8 1.9 1.0 2.3

65+ yrs 1.1 0.7 1.3 1.1 0.6 1.2 1.2 0.7 1.4

▪ Myocarditis/pericarditis reports per million mRNA vaccine doses administered by 

sex and dose number with no restrictions on post-vaccination observation time
30

VSD

Vaccine

Safety

Datalink

▪ 9 participating integrated healthcare organizations

▪ Data on over 12 million persons per year
31
32

VSD Rapid Cycle Analysis (RCA) safety monitoring

▪ Near real-time sequential (i.e., weekly) monitoring as data become 

available 

▪ Monitors a limited set of prespecified vaccine safety outcomes

▪ A public health surveillance activity, not the same as an 

epidemiologic study

▪ Designed to detect statistically significant associations and statistical 

signals (values above specified statistical thresholds), which do not 

necessarily indicate a safety problem

▪ Statistical signals detected through RCA require further evaluation
33

COVID-19 vaccine doses administered in the VSD 

(thru Jun 12, 2021)

4,551,160

total doses

5,781,728

total doses
34

COVID-19 vaccine doses administered by age group in the VSD 

(thru Jun 12, 2021)

Pfizer-BioNTech doses

▪ 12–15-year-olds

‒ 176,987 first doses

‒ 66,546 second doses

▪ 16–17-year-olds

‒ 127,665 first doses

‒ 101,938 second doses
35

VSD Rapid Cycle Analysis: Outcome events in the 21-day risk interval after either dose 

of any mRNA vaccine compared with outcome events in vaccinated comparators on 

the same calendar days

* Adjusted for VSD site, 5-year age group, sex, race/ethnicity, and calendar date. ne=not estimable

Pre-specified outcome event

Events in risk

interval

Adj 

Rate Ratio*95% CI Signal

Acute disseminated encephalomyelitis 2 . 0.07 - ne no

Acute myocardial infarction 578 0.99 0.85 - 1.15 no

Appendicitis 691 0.80 0.70 - 0.90 no

Bell’s palsy 493 0.97 0.83 - 1.15 no

Cerebral venous sinus thrombosis 5 1.15 0.23 - 6.67 no

Disseminated intravascular coagulation 28 0.65 0.35 - 1.20 no

Encephalitis / myelitis / encephalomyelitis 15 0.94 0.35 - 2.77 no

Guillain-Barré syndrome 8 0.57 0.16 - 2.15 no

Stroke, hemorrhagic 227 0.81 0.64 - 1.03 no

Stroke, ischemic 1009 0.98 0.87 - 1.10 no

Immune thrombocytopenia 45 1.03 0.59 - 1.85 no

Kawasaki disease 0 0.00 0.00 - 2.60 no

Myocarditis / pericarditis 75 1.07 0.70 - 1.67 no

Seizures 266 1.03 0.82 - 1.30 no

Transverse myelitis 3 1.88 0.17 - 55.81 no

Thrombotic thrombocytopenic purpura 5 1.39 0.27 - 8.02 no

Thrombosis with thrombocytopenia syndrome (TTS) 66 0.79 0.52 - 1.20 no

Venous thromboembolism 579 1.07 0.92 - 1.25 no

Pulmonary embolism 484 0.99 0.84 - 1.18 no

(thru Jun 12, 2021)
36

VSD age-stratified analysis: Chart confirmed myocarditis/pericarditis events in 12–

39-year-olds in the 21-day risk interval compared with events in vaccinated 

comparators on the same calendar days 

* Adjusted for VSD site, 5-year age group and then the single year of age for 12-19 year olds, sex, race/ethnicity, and calendar date

† Moderna COVID-19 Vaccine is not authorized in persons aged <18 years

‡ ne=not estimable, no events in comparison interval (22–42 days after final dose)

Vaccine (dose #)

Events in risk

interval

Adj

Rate ratio*95% CI

Any mRNA (both doses) 26 3.5 1.1–15.0

Any mRNA (dose 1) 8 3.7 0.8–23.4

Any mRNA (dose 2) 18 3.6 1.1–15.7

Pfizer-BioNTech (both doses) 10 1.2 0.3–6.2

Pfizer-BioNTech (dose 1) 3 1.6 0.2–12.6

Pfizer-BioNTech (dose 2) 7 1.5 0.3–7.7

Moderna (both doses)†

16 . 2.4–ne

‡

Moderna (dose 1) 5 . 0.8–ne

‡

Moderna (dose 2) 11 . 2.4–ne

‡

(thru Jun 5, 2021)
37

VSD age-stratified analysis: Chart confirmed myocarditis/pericarditis events in 

12–39-year-olds in the 7-day risk interval compared with events in vaccinated 

comparators on the same calendar days 

* Adjusted for VSD site, 5-year age group, sex, race/ethnicity, and calendar date

† Moderna COVID-19 Vaccine is not authorized in persons aged <18 years

‡ ne=not estimable, no events in comparison interval (22–42 days after final dose)

Vaccine (dose #)

Events in risk

interval

Adj

Rate ratio*95% CI

Any mRNA (both doses) 22 10.0 2.9–46.5

Any mRNA (dose 1) 4 6.2 0.9–69.8

Any mRNA (dose 2) 18 10.8 3.2–49.0

Pfizer-BioNTech (both doses) 7 2.4 0.4–24.9

Pfizer-BioNTech (dose 1) 0 0 0–20.4

Pfizer-BioNTech (dose 2) 7 6.0 1.1–53.6

Moderna (both doses)†

15 . 6.9–ne

Moderna (dose 1) 4 . 2.1–ne

Moderna (dose 2) 11 . 6.6–ne

(thru Jun 5, 2021)
38

Chart confirmed myocarditis/pericarditis cases in VSD by day of symptom 

onset since most recent mRNA COVID-19 vaccination, 12–39-year-olds

(thru Jun 5, 2021)

n=3 events in 

comparison window 

(22–42 days)

▪ Most likely clusters

‒ Days 0–5

‒ Days 0–3

‒ Days 0–6

▪ All have a p-value <0.000001

▪ Parameters for the scan

‒ Includes days 0–56

‒ Scans all possible windows of 

length 1–28 days

n=29 events in 

the 0-21 days 

post-vaccination
39

Myocarditis/pericarditis chart confirmed rates in VSD in 

21-day risk interval, 12–39-year-olds

Vaccine(s) (dose #) Cases

Doses 

admin

Rate per million 

doses

(95% CI)

mRNA (both doses) 26 3,418,443 8 (5.3–11.8)

mRNA (dose 1) 8 1,879,585 4.4 (1.9–8.8)

mRNA (dose 2) 18 1,538,858 12.6 (7.5–19.9)

Pfizer-BioNTech (dose 1) 3 1,211,080 2.6 (0.5–7.7)

Pfizer-BioNTech (dose 2) 7 958,721 8.0 (3.2–16.5)

Moderna (dose 1) 5 668,505 7.5 (2.4–17.6)

Moderna (dose 2) 11 580,137 19.8 (9.9–35.5)

(thru Jun 5, 2021)
40

Care and status of chart confirmed myocarditis/pericarditis cases in VSD 

within 0–21 days following mRNA COVID-19 vaccination (N=29)*

Care and status n (%)

Highest level of care received

Outpatient 1 (3.4)

Emergency department 4 (13.8)

Inpatient hospitalization 22 (75.9)

Intensive care unit (ICU) 2 (5.7)

Median length of hospital stay (days, range) 1 (0–13)

Discharged to home at time of chart review 29 (100)

Follow-up visit noted at time of chart review 27 (93.1)

Follow-up qualitative summary

Current symptoms 

▪ Nearly all follow-up visit notes indicated resolution of symptoms at the time of follow-up

▪ Of those that had follow-up ECG/echo, lab testing, most had returned to normal or baseline 

Ongoing treatment/plan

▪ Most follow-up visit notes indicate tapering of some medications (NSAIDS, prednisone, etc.)

▪ Notes indicated maintenance of colchicine and activity limitations for 3–6 months

* 3 of the 29 cases 

(10.3%) had a history 

of COVID-19 infection
41

Myocarditis/pericarditis rates based on ICD-10 coded cases 

in VSD in 21-day risk interval, ages 12–39 years old

(thru Jun 5, 2021)

Product (dose)

Female

cases

Female rates

per million doses

(95% CI)

Male

cases

Male rates

per million doses

(95% CI)

Any mRNA (both doses) 6 3.2 (1.2–6.9) 26 16.9 (11.0–24.8)

Any mRNA (dose 1) 2 1.9 (0.2–7.0) 4 4.7 (1.3–12.0)

Any mRNA (dose 2) 4 4.7 (1.3–12.0) 22 32.0 (20.1–48.5)

Pfizer-BioNTech (both doses) 1 0.8 (0.0–4.7) 11 11.1 (5.5–19.8)

Pfizer-BioNTech (dose 1) 1 1.5 (0.0–8.5) 1 1.8 (0.0–10.0)

Pfizer-BioNTech (dose 2) 0 . (. – . ) 10 23.0 (11.0–42.3)

Moderna (both doses) 5 7.1 (2.3–16.6) 15 27.5 (15.4–45.4)

Moderna (dose 1) 1 2.7 (0.1–14.9) 3 10.2 (2.1–29.9)

Moderna (dose 2) 4 12.2 (3.3–31.2) 12 47.7 (24.6–83.3)
42

Preliminary myocarditis/pericarditis crude reporting rates to 

VAERS following mRNA COVID-19 vaccination (data thru Jun 11, 2021)

Overall reporting

rate per million doses

Reporting rate in females

per million doses

Reporting rate in males

per million doses

Age groups All doses Dose 1 Dose 2 All doses Dose 1 Dose 2 All doses Dose 1 Dose 2

12-17 yrs 18.1 5.3 37.0 4.2 1.1 9.1 32.4 9.8 66.7

18-24 yrs 15.9 4.8 28.4 3.6 1.5 5.5 30.7 8.7 56.3

25-29 yrs 6.7 2.5 10.8 2.0 0.8 2.6 12.2 4.5 20.4

30-39 yrs 4.2 1.7 5.6 1.8 1.4 1.8 6.9 2.0 10.0

40-49 yrs 2.7 0.9 3.8 2.0 0.9 2.8 3.5 1.0 5.1

50-64 yrs 1.7 1.0 2.0 1.6 1.0 1.8 1.9 1.0 2.3

65+ yrs 1.1 0.7 1.3 1.1 0.6 1.2 1.2 0.7 1.4

▪ Myocarditis/pericarditis reports per million mRNA vaccine doses administered by 

sex and dose number with no restrictions on post-vaccination observation time
43

Summary
44

Summary

▪ Initial safety findings from Pfizer-BioNTech COVID-19 vaccination of 12–15-year-olds from v-safe and 

VAERS surveillance are consistent with results from pre-authorization clinical trials

▪ Analysis of VAERS preliminary reports of myocarditis/pericarditis is in progress, including follow-up to 

obtain medical records, complete reviews, apply CDC working case definition, and adjudicate cases

▪ Preliminary VAERS findings suggest:

‒ Median age of reported patients is younger for reports after dose 2 vs. dose 1

‒ Symptom onset clusters within the week following vaccination (mostly within 4 days)

‒ Predominance of male patients in younger age groups, especially after dose 2

‒ Observed reports > expected cases, especially after dose 2 in younger age groups

▪ Early VSD data for myocarditis/pericarditis in 12–39-year-olds also suggest:

‒ More cases after mRNA COVID-19 vaccination with dose 2 vs. dose 1

‒ Rate of 12.6 cases per million 2nd doses of any mRNA vaccine in the 21 days following vaccination

• Rates appear higher in males vs. females

‒ Clustering of myocarditis/pericarditis within the week following vaccination (most likely 0–5 days)

▪ Available outcome data indicate that patients generally recover from symptoms and do well
45

Next steps for assessing myocarditis/pericarditis 

following mRNA COVID-19 vaccination

▪ Continue monitoring in VAERS

‒ Follow-up to obtain medical records, conduct case reviews, apply CDC 

working case definition, and adjudicate case reports

‒ Surveillance review focusing on myocarditis and myopericarditis to describe 

epidemiology and characterize clinical features of cases is in progress

▪ Continue monitoring and assessment in VSD

‒ Quantify risk and characterize clinical features of cases

▪ Conduct follow-up on vaccine-associated cases to assess longerterm outcomes (i.e., at 3–6 months) 
46

CDC educational materials*

* CDC: https://www.cdc.gov/coronavirus/2019-ncov/vaccines/safety/myocarditis.html and https://www.cdc.gov/vaccines/covid-19/clinical-considerations/myocarditis.html
47

How to report an adverse event to VAERS

▪ Go to vaers.hhs.gov

▪ Submit a report online

▪ For help:

Call 1-800-822-7967

Email info@VAERS.org

video instructions 

https://youtu.be/sbCWhcQADFE

▪ Please send records to VAERS 

ASAP if contacted and asked

‒ HIPAA permits reporting of 

protected health 

information to public 

health authorities including 

CDC and FDA
48

Acknowledgments

Centers for Disease Control and Prevention

COVID-19 Vaccine Task Force

Vaccine Safety Team

Immunization Safety Office

Division of Healthcare Quality Promotion

Clinical Immunization Safety Assessment Project

Vaccine Safety Datalink

Food and Drug Administration

Center for Biologics Evaluation and Research 

We wish to acknowledge the contributions of investigators from the following organizations:
49
For more information, contact CDC

1-800-CDC-INFO (232-4636)

TTY: 1-888-232-6348 www.cdc.gov

The findings and conclusions in this report are those of the authors and do not necessarily represent the 

official position of the Centers for Disease Control and Prevention.

Thank you!